I am streaming movies from Amazon Web Service CloudFront.
I use JW Player so I use RTMP streaming and when platform doesn't support it (smartphones) it fallbacks to HTTP streaming.
I encode movies with Apple Compressor in .mp4 and H264/AAC

For now it's OK with RTMP (PC web browsers) but it's slow to start on my iPhone with HTTP streaming...
I supposed that it was because there is no "fast start" on Compressor for the .mp4 presets.

I tried a bad workaround: create a preset to encode a .mov file with fast start and change extension to .mp4 in Compressor a .mp4 the Compressor settings.
It worked in HTTP streaming but not at all for RTMP (the file is not read at all)

So is there a way to encode with Compressor to encode a .mp4 file H264/AAC optimized both for RTMP and HTTP streaming ?

While it can be plugged into QT and Compressor, I've seen much better results when using x264 in third part software such as Handbrake and MPEG Streamclip. Mind you they seem to be a heck of a lot faster than Compressor too. So faster and better = good. :D

Handbrake (which uses x264 by default) has the option "Web Optimized". When this is ticked
the header of the MP4 file is rearranged to optimize it for streaming across the web.

I'm not sure of the same option in MPEG Streamclip, but I'm sure it would have one.

I'd suggest running a small test file through handbrake and see how it goes.

[Andrew Stuckey]"I can highly recommend using the x264 codec for H264/mp4 format video rather than Apple's default H264 codec found in QT and Compressor. I've recently switched and seen far superior results."

[Andrew Stuckey]"I can highly recommend using the x264 codec for H264/mp4 format video rather than Apple's default H264 codec found in QT and Compressor. I've recently switched and seen far superior results."
I tried Handbrake but didn't get a better result than Compressor 4...
For what I have seen in my tests, contrast and chroma are better in Compressor 4. I got more details too in images.

I tried also Squeeze and didn't get much better results…

So I am still for now using Compressor 4 as the better choice for me... but when I see you guys saying that Apple's Compressor has one of the worst H264 codec I get confused…
;-)

What would be your encoder chart for .mp4 …264/AAC for Web diffusion at 1Mbs ?
For the moment, it could be something like that for me:
1 - Compressor 4
2 - Squeeze 8
3 - Handbrake
4 - MPEG Streamclip or ffmpegX

Apple's H264 codec is about the worst (least efficient) I know of.
MainConcept, used by Telestream Episode and Sorenson Squeeze, are better as is x264 and hardware accelerated encoders like Matrox MAX.

If you care about quality relative to bitrate, pick something other than Compressor.

I should mention that you can use x264 through Quicktime and certaing Matrox MAX through Compressor so if you like that interface you can use it with something other than Apple's H264.

[Craig Seeman]"MainConcept, used by Telestream Episode and Sorenson Squeeze, are better as is x264 and hardware accelerated encoders like Matrox MAX."I am not sure to fully understand :
do you recommend me to use MainConcept or x264 ?
(I use 1200kps and 700kps depending if the .mp4 movie is encoded for web browsers or for 3G smartphones)

Both are better than Apple's H.264. To take best advantage of x264 can require some "under the hood" encoding knowledge to tweak settings. Even using its defaults can get great results and if you want to stick with Compressor you can use x264 with it.

MainConcept, tied to the professional front end encoders such as Episode or Squeeze is a bit easier to use and you get an app that is far more flexible and deep than Compressor along with it.

Any of the above is better than Apple's H264 and even more so at lower bit rates which may be obvious down around 700kbps.

Compressor 4 creates H.264 .mp4. There's no reason to change the extension. The .mp4 templates can be duplicated and modified unlike the .m4v for iOS devices. Look under the HTTP Live Streaming presets.